Nova Per 2018 (= V392 Per) halted the decline from maximum when it was 2mag brighter than quiescence and since 2019 has been stable at such a plateau. The ejecta have already fully diluted into the interstellar space. We obtained BVRIgrizY photometry and optical spectroscopy of V392 Per during the plateau phase and compared it with equivalent data gathered prior to the nova outburst. We find the companion star (CS) to be a G9 IV/III and the orbital period to be 3.4118 days, making V392 Per the longest known period for a classical nova. The location of V392 Per on the theoretical isochrones is intermediate between that of classical novae and novae erupting within symbiotic binaries, in a sense bridging the gap. The reddening is derived to be E(B-V)=0.72 and the fitting to isochrones returns a 3.6Gyr age for the system and 1.35M_{sun}_, 5.3R_{sun}_, and 15L_{sun}_ for the companion. The huge Ne overabundance in the ejecta and the very fast decline from nova maximum both point to a massive white dwarf (M(WD)>=1.1/1.2M_{sun}_). The system is viewed close to pole-on conditions and the current plateau phase is caused by irradiation of the CS by the WD still burning at the surface.
We are presenting VRI photometry of 93 wide visual double stars having late B- or A- type primaries, taken from the Annex of Double and Multiple Stars of the HIPPARCOS Input Catalogue. Spectral types have been estimated for most of the primaries and for the majority of the secondaries. 40% of them probably have common origin components, for which we calculated photometric parallaxes and some orbital values estimates.
We present here multiband photometry for over 2000 Main-Belt asteroids. For each target, we report the probabilistic taxonomy using the measured V-R and V-I colors in combination with a machine-learning-generated decision surface in color-color space. Through this method, we classify >85% of our targets as one the four main Bus-DeMeo complexes: S-, C-, X-, or D-type. Roughly one-third of our targets have a known associated dynamic family, with 69 families represented in our data. Within uncertainties, our results show no discernible difference in taxonomic distribution between family members and non-family members. Nine of the sixty-nine families represented in our observed sample had 20 or more members present, and therefore, we investigate the taxonomy of these families in more detail and find excellent agreement with the literature. Out of these nine well-sampled families, our data show that the Themis, Koronis, Hygiea, Massalia, and Eunomia families display a high degree of taxonomic homogeneity and that the Vesta, Flora, Nysa-Polana, and Eos families show a significant level of mixture in taxonomies. Using the taxonomic purity and the degree of dispersion in observed colors for each of the nine well-sampled collisional families, we also speculate which of these families potentially originated from a differentiated parent body and/or is a family with a possible undetermined nested family. In addition, we obtained sufficient photometric data for 433 of our targets to extract reliable rotation periods and observe no obvious correlation between rotation properties and family membership.
Thanks to its proximity, alpha Centauri is an outstanding target for an imaging search for extrasolar planets. We searched for faint comoving companions to alpha Cen located at angular distances of a few tens of arcseconds, up to 2-3 arcmin. We obtained CCD images from the NTT-SUSI2 instrument in the Bessel V, R, I, and Z bands, and archive data from 2MASS.
We report on the environmental dependence of properties of galaxies around the RDCSJ0910+54 cluster at z=1.1. We obtained multi-band wide-field images of the cluster with Suprime-Cam and MOIRCS on Subaru and WFCAM on UKIRT. Also, an intensive spectroscopic campaign was carried out using LRIS on Keck and FOCAS on Subaru. We collected 161 spectra with secure redshifts, with which we calibrated a larger sample of photometric redshifts.
We present a discovery of definitive large-scale structures around RX J0152.7-1352 at z=0.83 based on spectroscopic redshifts. In our previous papers, we reported a photometric identification of the large-scale structures at z~0.8. A spectroscopic follow-up observation was carried out on eight selected regions covering the most prominent structures to confirm their association to the main cluster. In six out of the eight fields, a well-isolated peak is identified in the distribution of spectroscopic redshifts at or near the cluster redshift. This is strong evidence for the presence of large-scale structures associated to the main cluster at z=0.83.
We have obtained VR photometry of 282 Cepheid variable star candidates from the northern part of the All Sky Automated Survey (ASAS). These together with data from the ASAS and the Northern Sky Variability Survey (NSVS) were used to redetermine the periods of the stars.
AA Tau has been monitored for more than 20 years since 1987, exhibiting a nearly constant brightness level of V=12.5mag. We report here that in 2011 it suddenly faded away, becoming 2 magnitudes fainter in the V-band, and has remained in this deep state since then. We investigate the origin of the sudden dimming of the AA Tau system. We report new optical and near-IR photometry and spectroscopy obtained during the fading event.
We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f=71.7(+/-4.4)%. From the O-C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67(+/-0.20)yr may result from magnetic activity cycles, which are identified by the variability of Max. I-Max. II. Another sinusoidal variation (i.e., A=0.0131days(+/-0.0009days) and P3=24.16(+/-0.64)yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt=+9.79(+/-0.80)*10^-8days/yr, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J_spin_>(1/3)J_orb_.
We present charge-coupled device (CCD) photometry for the short-period K-type binary EI CVn, observed on 2009 February 28 at the Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences. By using the Wilson-Devinney program, the photometric solution was first deduced from our VR observations.
